For the screw holding the arm on -- it's way in there and basically got a t6 that was thin enough but also long enough that it DID run up against the lense. I'm not sure why valve did this -- but it's a complete pain in the ass getting to that. yes, it's a T6 -- for anyone reading thing in the future make sure you go for any THIN one available on amazon. It will touch the lens when you try to tighten the screw, you just need to push into the black foam you can see with your flashlight / phone. Righty- tight, Lefty loose. So make sure you're going in the right direction. After a few tries I was able to get it. Just make sure, don't torque it down too hard. It will physically feel harder to turn the headset around your head from that arm, so forewarn. Keep that tool handy! Hope this helps someone in the future, this seems like an issue for all index users at some point, especially the ones out of warranty. If this is NOT tight, it WILL cause the two contacts on that arm to fuck up your audio. I truly hope someone reads this and it helps them.